Radiation cameras

Abstract

The invention describes radiation cameras consisting of interlaced scintillation fiber arrays and a fiber readout method using pixellated photo-detector cameras. Several fabrication methods of the fiber arrays are described. The use of such Radiation Cameras in Medical Imaging systems is also described.

1. A Tomographic Radiation Imaging System, without collimators, for detecting the positions of sources of gamma or X-rays hereinafter referred to as electromagnetic radiation, comprising:
 a) track detectors for registering tracks of electrons created by the interaction of the electromagnetic radiation with said track detectors wherein said track detectors comprise:
 a1) structures composed of two or three interlaced two dimensional scintillation fiber arrays, wherein each array is orthogonal to the other two arrays wherein
 a11) the fiber cross section is one of circular and rectangular and less than (100μ) 2 , and 
 a12) said scintillation fibers are non-touching and separated by a material with a refractive index of less than n=1.10, and 
 
 
 b) position sensitive detectors of electromagnetic radiation, and 
 c) photo-detector digital Cameras hereinafter referred to as Cameras, wherein
 c1) each photo-detector element of a Camera is optically coupled to one of the scintillation fibers on a one-to-one basis, and wherein 
 c2) the end of each of the scintillation fibers not connected to a photo-detector is coated with a light reflecting coating, and 
 
 d) Camera readout electronics for identifying the photo-detector pixels that, within a predetermined time window, generate an electric signal following a scintillation event, and 
 e) time coincidence circuits for correlating separate tracks in the track detector and signals detected by the position sensitive detectors, and 
 f) an electronics interface containing position electronics for registering in real time the absolute position and direction of the Radiation Imaging System, the coincidence circuits, the readout electronics of the Photodetector cameras, temporary memory and communication means for relaying the outputs of the Cameras to an external computer for building a Tomographic image of the Radiation sources. 
 
     
     
       2. A Tomographic Radiation Imaging System as in  claim 1  whereas the external computer communicating with the electronics interface uses a method for mapping a Tomographic image of Radiation sources by calculating:
 a) the beginning and direction of the electron tracks by a best fit to a straight line of the initial, substantially straight section of the track, after correcting the large deviations due to Coulomb scattering, as imaged in the orthogonal projections registered by the Cameras, and 
 b) the range of the electron by adding the shortest distances between the fibers traversed by the electron, weighted by the amplitude of the respective signals in each fiber, and 
 c) the energy deposited on the track by adding the amplitude of the respective signals registered by the Cameras, and 
 d) the compton scattered electron tracks by their coincidence with position sensitive detectors and lack of very short x-ray electron track in the close proximity of their end, and 
 e) the photo-electric tracks by their lack of coincidence with position sensitive detectors and the existence of a very short x-ray electron track in the close proximity of their end, and 
 f) the direction of the scattered electromagnetic radiation as the line joining the beginning of the scattered electron track and the beginning of the electron track in coincidence, and 
 g) the direction of the scattered electromagnetic radiation as the line joining the beginning of the scattered electron track and the pixel of the position sensitive detector where a signal in coincidence with the track detector was registered, and 
 h) the direction and energy of the primary electromagnetic radiation interacting with the track detector from the direction and range of the scattered electron and the direction and energy of the scattered electromagnetic radiation in coincidence, and 
 i) the direction and energy of the primary electromagnetic radiation interacting with the track detector, from the direction and energy of the scattered electron and the direction and energy of the scattered electromagnetic radiation in coincidence, and 
 j) the direction and energy of the primary electromagnetic radiation interacting with the track detector from the direction and energy of the scattered electron and the direction and energy of the scattered electromagnetic radiation in coincidence as detected by the same track detector, and 
 k) the direction and energy of the primary electromagnetic radiation interacting with the track detector from the direction and energy of the scattered electron and the direction and energy of the scattered electromagnetic radiation as detected by the track detector and the position sensitive detectors in coincidence, and 
 l) the intersection points in 3D of the directions of all the primary electromagnetic radiations interacting with the track detector, and 
 m) builds a 3D map of the intersection points. 
 
     
     
       3. A Tomographic Radiation Imaging System as in  claim 1  wherein the track detectors comprise scintillation fibers belonging to one of a group of plastic scintillator fibers, plastic scintillator fibers loaded with another scintillator material, plastic scintillator fibers loaded with a material that has a resonant absorption to a specific energy, plastic scintillator fibers loaded with a high Z material, glass scintillator fibers, glass scintillator fibers loaded with another scintillator material, glass scintillator fibers loaded with a material that has a resonant absorption to a specific energy, glass scintillator fibers loaded with a high Z material, fibers composed of scintillator material powder within a plasticised carrier and a scintillator material in a fiber form. 
     
     
       4. A Radiation Imaging System as in  claim 3  wherein the spectrum of the electromagnetic radiation source is given by the energies of the tracks that are not compton scattered electron tracks, and are not in coincidence with the position sensitive detectors. 
     
     
       5. A Tomographic Radiation Detecting System as in  claim 1  wherein the distance between the non-touching fibers is larger than the fiber diameter. 
     
     
       6. A Tomographic Radiation Detecting System as in  claim 1  wherein the position sensitive detectors comprise:
 a) one of a 2D pixellated array of high density, high Z scintillating crystals comprising LaBr 3 , LaClBr 2 , Lu 2 SiO 5 , Lu 3 Al 5 O 12 ,Y 2 Gd 2 O 3 , Bi 4 Ge 3 O 12  s and 
 b) a photo-detector Camera wherein each pixel of the camera is optically coupled to one of the pixels of the 2D pixellated array. 
 
     
     
       7. A Tomographic Radiation Detecting System as in  claim 1  wherein the position sensitive detectors comprise one of HgI 2 , CZT, Si, or Ge semiconductor detectors. 
     
     
       8. A Tomographic Radiation Detecting System as in  claim 1  wherein the position sensitive detectors comprise fibers loaded with high Z scintillator material optically coupled to the photodetectors of a digital camera, on a one-to-one basis. 
     
     
       9. A Tomographic Radiation Imaging System as in  claim 1  wherein adjacent fibers in each two dimensional layer of fibers are grouped into two subgroups of odd and even fibers according to their geometrical positions along the array, and wherein each of the two subgroups are optically coupled to different photo-detector Cameras through their respective non-coated ends such as the fiber structure formed by two interlaced structures composed of “odd” and “even” fibers are optically coupled to different and separate cameras, and wherein
 the coordinates of the pixels forming the electron track are obtained by the two fiber structures separately, and 
 determining the coordinates of the pixels forming the track by combining the pixels determined separately by both cameras. 
 
     
     
       10. A Tomographic Radiation Imaging System as in  claim 1  for high resolution X-Ray imaging wherein the diameter of the fibers are less than 10μ comprising:
 a) an X-Ray tube with a conical beam emitting a wide spectrum of x-rays and 
 b) a data processor for calculating:
 b1) transmission X-Ray images as a function of spectral bands, by mapping the coordinates of the beginnings of the non-scattered electron tracks that are in the direction of the X-Ray source, wherein the track range indicates the energy band, and 
 b2) scattered X-ray images by mapping the coordinates of the intersections of the directions of the non-scattered tracks that are not in the direction of the X-Ray source wherein the track range indicates the energy of the scattered X-rays, and 
 b3) the relative densities of the body absorbing and scattering the X-rays from the transmission and scattering X-ray images at the different energy bands. 
 
 
     
     
       11. An X-ray Radiation Imaging system as in  claim 10  for Mammography comprising:
 a) an X-ray source, and 
 b) a Tomographic Radiation Imaging system in front of the X-ray source and across the breast protruding through an opening of a bed, on which a patient lies, face down, for obtaining an X-ray transmission image of the breast, and 
 c) One or more Tomographic Radiation Imaging systems orthogonal to the first system and the direction of the X-ray beam, for obtaining scattered X-ray images of the breast, and 
 d) A turn-table that holds the x-ray source and the Tomographic Radiation systems and rotates around the breast in fixed steps, and 
 e) A data processor for building a composite image of the scattering centers of the breast from the superposition of the images obtained from the various angles by the Tomographic Radiation Imaging systems. 
 
     
     
       12. An X-ray Radiation Imaging system as in  claim 11  for Mammography for imaging the breast parts close to the cage and arm-pits comprising:
 a) an X-ray source directed towards the cage and arm-pits, and 
 b) One or more Tomographic Radiation Imaging systems facing the cage and arm-pits but shielded from the X-ray source, and 
 c) A turn-table that holds the Tomographic Radiation systems and rotates around the breast in fixed steps, and 
 d) A data processor for building a composite image of the scattering centers of the breast from the superposition of the back-scattered images obtained from the various angles by the Tomographic Radiation Imaging systems. 
 
     
     
       13. A Tomographic Radiation Imaging System as in  claim 1  for high resolution X-Ray imaging of a body comprising:
 a) an X-Ray tube with a parallel beam emitting a wide spectrum of x-rays, and 
 b) a track detector comprising a single array of non-touching plastic scintillation fibers where the diameter of the fibers is less than 10μ and where the long dimension of the fibers are in the direction of the parallel X-Ray beam, and 
 c) a Data processor for mapping:
 c1) transmission X-Ray images as a function of spectral bands, by mapping the coordinates of the beginnings of the non-scattered electron tracks that are in the direction of the X-Ray source, wherein the track energy indicates the specific energy band of the x-ray source. 
 
 
     
     
       14. A Tomographic Radiation Imaging System as in  claim 1  for a high resolution Positron Emission Tomography imaging of a body wherein said system is of such dimensions that it can be inserted within a Computerized Tomography torus or a Magnetic Resonance Imaging machine and placed in close proximity to the body organ emitting 511 keV gamma rays, and comprises:
 a) a track detector where the diameter of the fibers is less than 10μ, and 
 b) position sensitive detectors viewing the faces of the track detector not obstructed by the Cameras optically coupled to the fiber arrays, and 
 c) a Data processor for mapping the intersection of the directions of the gamma rays detected by the track detector and the position sensitive detectors in coincidence. 
 
     
     
       15. A method for detecting the positions of sources of gamma or X-rays comprising:
 a) a track detector for determining the coordinates of an electron track created by the interaction of the electromagnetic radiation wherein said track detector comprises:
 a1) a solid, high brilliance scintillator, and 
 a2) optical systems for projecting the 3D track images on 2D planes situated on two orthogonal directions from said scintillator, each from two diametrically symmetric directions, and 
 a3) digital cameras placed at the focal points of said optical systems, for imaging tracks within the solid scintillator, from each of the four symmetric directions, and 
 
 b) pixellated position sensitive detectors placed at solid angles not covered by the optical systems, and 
 c) time coincidence circuits for correlating tracks in the track detector with signals detected by the position sensitive detectors, and 
 d) a data processor wherein said data processor:
 d1) calculates for each track event the actual distance of the track from the respective sets of optical systems, by comparing the number of photons detected by the respective cameras from each of the symmetrically opposite directions, and 
 d2) deconvolves for every track event the blurred image obtained by each of the static cameras, by a Point Spread Function of the track for a given distance, as projected by the optical system on the digital cameras, and 
 d3) calculates:
 d31) the beginning, and direction of the electron tracks by a best fit to a straight line of the initial, substantially straight section of the track, after correcting the large deviations due to Coulomb scattering, as imaged in the orthogonal projections registered by the Cameras, and 
 d32) the energy deposited on the track by adding the amplitude of the respective signals registered by the Cameras, and 
 d33) the compton scattered electron tracks by their coincidence with the position sensitive detectors and lack of very short x-ray electron track in the close proximity of their end, and 
 d34) the photo-electric tracks by their lack of coincidence with position sensitive detectors and the existence of a very short x-ray electron track in the close proximity of their end, and 
 d35) the direction of the scattered electromagnetic radiation as the line joining the beginning of the scattered electron track and the beginning of the electron track in coincidence, and 
 d36) the direction of the scattered electromagnetic radiation as the line joining the beginning of the scattered electron track and the pixel of the position sensitive detector where a signal in coincidence with the track detector was registered, and 
 d37) the direction and energy of the primary electromagnetic radiation interacting with the track detector from the direction and range of the scattered electron and the direction and energy of the scattered electromagnetic radiation in coincidence, and 
 d38) the direction and energy of the primary electromagnetic radiation interacting with the track detector, from the direction and energy of the scattered electron and the direction and energy of the scattered electromagnetic radiation in coincidence, and 
 d39) the direction and energy of the primary electromagnetic radiation interacting with the track detector from the direction and energy of the scattered electron and the direction and energy of the scattered electromagnetic radiation in coincidence as detected by the same track detector, and 
 d310) the direction and energy of the primary electromagnetic radiation interacting with the track detector from the direction and energy of the scattered electron and the direction and energy of the scattered electromagnetic radiation as detected by the track detector and the position sensitive detectors in coincidence, and 
 d311) the intersection points in 3D of the directions of all the primary electromagnetic radiations interacting with the track detector, and 
 d312) builds a 3D map of the intersection points.